package org.apache.lucene.index;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.util.ArrayUtil;
import org.apache.lucene.search.Similarity;

/** Taps into DocInverter, as an InvertedDocEndConsumer,
 *  which is called at the end of inverting each field.  We
 *  just look at the length for the field (docState.length)
 *  and record the norm. */

final class NormsWriterPerField extends InvertedDocEndConsumerPerField implements Comparable<NormsWriterPerField> {

    final NormsWriterPerThread perThread;
    final FieldInfo fieldInfo;
    final DocumentsWriter.DocState docState;

    // Holds all docID/norm pairs we've seen
    int[] docIDs = new int[1];
    byte[] norms = new byte[1];
    int upto;

    final FieldInvertState fieldState;

    public void reset() {
        // Shrink back if we are overallocated now:
        docIDs = ArrayUtil.shrink(docIDs, upto);
        norms = ArrayUtil.shrink(norms, upto);
        upto = 0;
    }

    public NormsWriterPerField(final DocInverterPerField docInverterPerField, final NormsWriterPerThread perThread, final FieldInfo fieldInfo) {
        this.perThread = perThread;
        this.fieldInfo = fieldInfo;
        docState = perThread.docState;
        fieldState = docInverterPerField.fieldState;
    }

    @Override
    void abort() {
        upto = 0;
    }

    public int compareTo(NormsWriterPerField other) {
        return fieldInfo.name.compareTo(other.fieldInfo.name);
    }

    @Override
    void finish() {
        if (fieldInfo.isIndexed && !fieldInfo.omitNorms) {
            if (docIDs.length <= upto) {
                assert docIDs.length == upto;
                docIDs = ArrayUtil.grow(docIDs, 1 + upto);
            }
            if (norms.length <= upto) {
                assert norms.length == upto;
                norms = ArrayUtil.grow(norms, 1 + upto);
            }
            final float norm = docState.similarity.computeNorm(fieldInfo.name, fieldState);
            norms[upto] = docState.similarity.encodeNormValue(norm);
            docIDs[upto] = docState.docID;
            upto++;
        }
    }
}
